How many 4-digit combinations can be made out of the numbers 1 2 3 4 5 6 7 8 without repeating the numbers in the same digits can you give me all sequences from 1 through 8 jnieves1262@aol. com you

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?